Patent Literature 1 discloses a stacked polymer electrolyte battery including an electrode group and short-circuiting and a heat radiation accelerating units. The units are formed by arranging two metal plates outside the electrode group each via an insulator. The battery of Patent Literature 1 is thought to be able to reduce the voltage across its electric element and to smoothly release heat generated in the unit etc. to the outside when the electrodes are short-circuited by nailing etc., by an application of a short-circuit current to the short-circuiting and heat radiation accelerating unit. Patent Literatures 2 and 3 also disclose various techniques to inhibit heat generation due to internal short circuit of batteries occurred by nailing etc.